Accused killer Jared Lee Loughner, 22, signed at least one of the pieces of paper, which he put in a single envelope and placed in the safe at his parents’ modest one-story home in the northwest section of the city, according to charges filed yesterday in federal court in Phoenix.

He soon enrolled at Pima Community College, where his wacko behavior immediately alarmed students and professors.

Pima officials said in a statement that from February to September 2010, campus cops were called on Loughner five times because of classroom and library disruptions.

He was suspended after college police discovered a YouTube video in which Loughner claimed the college was “illegal.”

Along with the suspension came a terse letter to Loughner’s parents stating if he wanted to come back, he’d have to “obtain a mental-health clearance” from a professional,” the school said. Loughner dropped out instead.

Pima math teacher Ben McGahee said Loughner worried him.

“I always felt, you know, somewhat paranoid,” McGahee told The Washington Post. “When I turned my back to write on the board, I would always turn back quickly — to see if he had a gun.”

An older student in the class, Lynda Sorenson, 52, was scared stiff of the lunatic. She wrote e-mails — provided to The Washington Post — alluding to Loughner’s antics.

“He scares me a bit . . . Hopefully he will be out of class very soon, and not come back with an automatic weapon,” she wrote on June 1, the first day of class.

The feds are reportedly looking into whether he joined an anti-Semitic, anti-government hate group.

According to a Department of Homeland Security memo, the agency is trying to determine whether Loughner is linked to the fanatical group American Renaissance, Fox News reported The group promotes views that are “anti-government, anti-immigration, anti-ZOG (Zionist Occupation Government), anti-Semitic,” the memo says.

Giffords is “the first Jewish female elected to such a high-position in the US government. She was also opposite the group’s ideology when it came to immigration debate,” according the memo.

Jared Taylor, editor of American Renaissance, vehemently denied any association with Loughner.

Loughner grew up in a neighborhood of ranch-style and split-level homes, with parents whom neighbors described as loners.

Neither of Loughner’s parents was home yesterday.

Loughner could face death by lethal injection if he’s convicted of murder in the horrific shooting case. He’ll be arraigned today in federal court in Phoenix.